Mole ConceptHard
Question
Which of the following statements is/are correct ?
Options
A.21.2 g sample of impure Na2CO3 is dissolved and reacted with a solution of CaCl2, the weight of precipitate of CaCO3 is 10.0 g. the % purity of Na2CO3 is 50%.
B.The percentage purity of Na2CO3 is 60%
C.The number of moles of Na2CO3 = CaCO3 = 0.1 mol.
D.The number of moles of NaCl formed is 0.1 mol.
Solution
Mw of CaCO3 = 100, Mw of Na2CO3 = 106
Mw of HNO3 = 63 g mol-1
Na2CO3 + CaCl2 → CaCO3 + 2NaCl
a. moles of CaCO3 =
= 0.1 mol
moles of Na2CO3 = moles of CaCO3 ≡ 2 × moles of NaCl
Weight of Na2CO3 = 0.1 × 106 = 10.6 g
% purity Na2CO3 =
× 100 = 50%
b. Wrong.
c. Correct.
d. moles of NaCl = 2 × 0.1 = 0.2 mol
Mw of HNO3 = 63 g mol-1
Na2CO3 + CaCl2 → CaCO3 + 2NaCl
a. moles of CaCO3 =
= 0.1 molmoles of Na2CO3 = moles of CaCO3 ≡ 2 × moles of NaCl
Weight of Na2CO3 = 0.1 × 106 = 10.6 g
% purity Na2CO3 =
× 100 = 50%b. Wrong.
c. Correct.
d. moles of NaCl = 2 × 0.1 = 0.2 mol
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